Electrical connector



B. A. EELS ELECTRICAL CONNECTOR Filed April 2o, 1945 2 Sheets-Sheet l INI/mms."

, BASIL A. BELS ATT-OREY July 8, 1947. a. A. BELs 2,423,548"` ELEcTRcALcoNNEcToR Filed April 20, 1945 2.Sheets-Sheet 2 -p HILI INVENTOR. 35 BASIL A. BELS ATTORNEY Patented July 8, 1947 ELECTRICAL CONNECTOR Basil A. Bels, Great Neck, N. Y., asslgnor, by mesne assignments, to Hazeltine Research, Inc., Chicago, Ill., a corporation of Illinois Application April 20, 1945, Serial No. 589,432

7 Claims. l

The present invention relates to electrical connectors and, particularly, to such connectors which are adapted to engage an approximately cylindrical conductive contact member. While the invention is of general application, it has particular utility as an electrode terminal connector for use with vacuum tubes oi' the type having an electrode terminal sealed through, or directly supported by, a wall of an evacuated glass envelope and will be described in that connection,

It frequently is desirable to provide an electrical connector adapted to engage an approximately cylindrical conductive contact member. No essential problem is encountered in a simple connector of this type when the only requirement to be met is that of providing a positive consistent electrical contact with the contact member. However, problems of design arise when the connector must additionally provide adequate and consistent thermal contact with the contact member to enable substantial conduction of thermal energy therebetween and particularly is this true when the force required to effect complete engagement between the contact member and the connector must be minimized. The

problems thus raised are multipliedlwhere the connector must at the same time allow for some eccentricity of the contact member and for lateral and angular departures from coincidence oi' the axes of the contact member and connector.

To illustrate by example the problem encountered in providing an electrical connector of the type described.` consider the case of an electrical connector for a vacuum tube of the type having an anode terminal sealed through or supported by one wall o f a glass envelope. The

- power handled bythe tube may be sui'iiciently large that the anode terminal heats so excessively as to fracture the glass seal unless' precautions are taken to conduct thermal energy rapidly ,away from the anode terminal. The anode lterminal connector in such case must not only provide the required electrical connection to the, anode terminal, but additionally must firmly engage most of surface of the latter and be capable of furnishing a path of low thermal resistance to a them-al-dissipative surface it adequate cooling of the anode terminal is to be..

eiected. This usually presents no undue problem if the anode connector is of split construction adapted to beL placed over the anode terminal and clamped thereto. Where, however, it is -required that the anode connector be simply slipped bodily over the anode terminal without subseing the manner of attaining the required rm thermal contact over a largecontaot area particularly since the force required to effect complete engagement of the connector and terminal cannot be large without danger of fracture of the tube glass envelope.

In many such applications. it is further necessary that the vacuum tube be physically inserted axially into operative position and that, during such insertion, the anode terminal and possibly one or more electrode terminals fully engage xed electrical connectors provided therefor. The anode terminal in these tubes usually is positioned axially of the tube envelope at the inserted end thereof. It is quite difllcult in practice accurately vto center and axially to align the anode terminal at the 'time it is sealed to the glass envelope of the tube. The anode terminal connector consequently must additionally be capable of permitting small lateral and angular departures from coincidence of the axes of the terminal and connector without placing undue strain on the terminal since this strain would be transmitted directly to the glass seal and would tend to fracture it.

It is an object of the present invention therefore to provide a new and improved electrical connector adapted to engage an approximately cylindrical conductive contact member.

It is a further object of the invention to pro vide a new and improved electrical connector, adapted to engage an approximately cylindrical conductive contact member, having greater thermal conductivity than has readily been heretofore obtainable in a connector of the type described.

It is an additional object of the invention to provide an electrical connector, adapted to engage an approximately cylindrical conductive contact member, oi improved and relatively inexpensive construction.

It is another object of the invention to provide a new and improved electrical connector. adapted to engage an approximately cylindrical conductive contact member, which ensures positive,

e consistent and substantially uniform electrical and thermal contact with such contact member` while minimizing the force required to eilect comthe connector and, at the same time, permitting relative lateral and angular departures from coincidence of the axes of the contact member and connector.

In accordance with one form of the invention, f e quent clamping, serious problems'arise concern- 5l an electrical connector, adapted to engage an f' maar approximately cylindrical contact member, comprises stacked laminations oi resilient conductive material having nested V-shaped contact fingers arched normal to the plane of lamination and extending radially with respect to a common axis to provide at their inner ends a cylindrical laminated contact surface normally symmetrical about such common axis but deformable to maintain coincidence of the axis of fthe contact surface with that of the contact member when the latter is positioned in engaging relation with the contact surface. 'I'he connector is thus adapted to ensure consistent and substantially uniform electrical and thermal contact with the contact member while minimizing the force required to effect complete engagement of the member with the connector.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

Referring now to the drawings, Fig. 1 illustrates a high-frequency wave-signal oscillator which utilizes electrical connectors embodying the present invention; Fig. 2a is an enlarged cross-sectional side view of a portion of the electrical connector of the present invention, while Fig. 2b is a top view of the stacked laminations thereof; and Fig. 3 illustrates a method of forming the connector laminations.

Referring now more particularly to Fig. 1 of the drawings, there is illustrated a high-frequency wave-signal oscillator which utilizes electrical connectors embodying the present invention. This oscillator is disclosed and claimed in a copending application of Harold A. Wheeler, entitled Ultra-short-wave signal-translating device, Serial No. 565,828, filed November 30, 1944, and assigned to the same assignee as the present application. Reference is made to this copending application for a detailed description of the oscillator and its mode of operation. Briefly, the oscillator includes a first or anode cavity resonator I and a second or cathode cavity resonator I I which is capacitively coupled to the resonator I0 by a probe I2 arranged to extend through an aperture I3 in a diaphragm I4 separating the cavity resonators Ill and II. The cavity resonator I0 includes a cylindrical hollow outer conductor I5 and a cylindrical hollow inner conductor I5 which are maintained in fixed coaxial relationship by insulating spacers I'l secured between the conductors I5 and I6 at points suitably spaced around the circumference thereof. One end of the inner conductor I6 is closed by a disc Il which forms one element of an electrical connector embodying the present invention and presently to be described in greater detail. Brief- (Il ly considered for purposes of the present description, the disc IB has a centrally positioned concentric aperture with a concentric shoulder Ila upon which is secured by machine screws IIb a stack of laminations IS more fully described herelnafter The outer conductor I5 of the cavity resonator is ^losed at its end opposite the diaphragm I4 by a disc 2I which supports, in coaxial relation with the conductor I5, a cylindrical conductor 22 of diameter appreciably smaller than that of the inner conductor I6. 'I'he conductor 22 effectively forms a re-entrant portion of the outer conductor I5 and is used for purposes of tuning the resonator Ill.

The second or cathode resonator II similarly includes an outer hollow cylindrical conductor Il', which may be an extension of the conductor Il, and an inner hollow cylindrical conductor 2l which is supported by a conductive ring 2l in coaxial relation with the outer conductor Il'. A conductive ring 25 is positioned between and electrically engages the inner and outer conductors 22 and I5', this ring being adjustable axially along these conductors for purposes of tuning thc cathode cavity resonator. The end of the inner conductor 23 adjacent the diaphragm Il is closed by a disc 2l having a centrally positioned coaxial aperture and forming an element of an electrical connector 21 similar in construction to that of the electrical connector 2l. The diaphragm Il likewise has a centrally positioned coaxial aperture in which is secured an electrical connector 2l oi' a type disclosed and claimed in applicant's copending application entitled Electrical connector, Serial No. 571,610, flied January 6, 1945, and assigned to the same assignee as the present application.

A vacuum tube 2l has an approximately cylindrical conductive contact member or anode terminal Il hermetically sealed to one end of a cylindrical glass envelope portion II. a conductive grid terminal disc l2 which is hermetically sealed between the envelope portion II and a second cylindrical glass envelope portion Il. and a conductive cathode terminal 24 sealed to one end of theglasslenvelope portion 32. 'I'he tube 2! is insertable axially through the center o1 the hollow conductor 2l of the cathode cavity resonator II into operative position with its anode terminal Il engaging the electrical connector 2l, its grid terminal disc I2 engaging the electrical connector 2l and its cathode terminal Il engaging the electrical connector 21. Por purposes o( simplicity, certain electrical connectors which extend out of the dat base ofthe tube 2'! are not shown nor is the means shown for maintaining tube 25 in the operative position described.

Reference is made to the aforementioned copending Wheeler application for a detailed description of the oscillator described. Briefly considered, oscillations developed in the cathode cavity resonator II are repeated 4by the vacuum tube 2l to the anode cavity resonator Il and a portion of the oscillatory energy developed in the latter ls applied by the probe I2 back to the cathode cavity resonator II to maintain sustained oscillation of the oscillator.

During operation of the oscillator, it is necessary that the anode terminal Il of the tube 2l be electrically connected by the electrical connector 20 through the disc Il thereof and the inner conductor I5 of the anode cavity resonator I0 to a. source of anode potential indicated as +B. The vacuum tube 2! during operation translates sufficient power that the temperature of the anode terminal 30 is raised to a high value. There is consequently danger of fracturing the glass seal between the anode terminal 3l and the tube envelope portion 3l unless thermal energy is conducted rapidly away from the anode terminal. Hence, it is necessary that the electrical connector 20 make good thermal contact with the anode terminal I0 over a maior portion of the surface of the latter and that the connector provide a path of good thermal conductivity to the conductor I5 in order that the latter may act as thermal radiators to maintain the anode terminal 30 at a relatively low safe temperature.

An additional requirement of the electrical connector 20 is that it must accommodate eccentricities of the anode terminal Iland permit relative departure's from coincidencefot the axes of the-anodeterminaland the connector while the vacuum tube 29 is in its operative position in the oscillator and also'v during insertion and withdrawal thereof. Otherwise a mechanical strain is placed upon the anode terminal' 30 which mayfracture the seal betweenthe anode terminal and the tube envelope portion 3i'. For a like reason,

the electrical connector 20 `must minimize the l0 force required to effect complete engagement and disengagement of the anode terminal' 30 with the connector.

` Certain of the requirements ylast mentioned with relation to the electrical connector n apply, though to alesser degree, to the electrical connectors 21 and 23.

Considering now in greater particularity the portion of the oscillator arrangement described which embodies the present invention, a portion of the electrical connector 201s illustrated in enlarged cross-sectional side view in Fig. 2a and in top view in Fig. 2=b. The connector, which asy heretofore explained is adapted to engage the approximately cylindrical conductive contact member-30, comprises stacked laminations I9 of resilient conductive material having nested V- shaped contact lingers 35 arched normal to the plane of lamination and extending radially with respect to a common axis o-o to provide at their inner ends a cylindrical laminated contact surface S normally symmetrical about the common axis o-o but deformable to maintain coincidence of the axis of the contact surface S with that of the contact member 30 when the member is posi.- tioned in engaging relation with the surface S. The material of the laminations I9 may. for example, be beryllium copper and each lamination preferably is silver-plated to reduce the resistance of the connector for high-frequency wave signals. The connector includes vring-shaped spacing laminations 38 inserted between the laminations I9 at the outer ends of the contact lingers 35. It is the purpose of the'spacing laminatlons 33 to maintain the laminations* I3 slightly spaced along the entire lengths oi' the contact fingers 35 to permit increased conjoint flexibility of the laminations at the inner ends of the fingers so that the latter, over a limited range of movement, may flex: individually. Each I of the laminations I9 is formed of sheet material having a concentric indentation 31 of V-shaped cross section, normal `to the plane of lamination, formed in one face thereof, as by arolling, spinning or stamping operation, to. a depth much greater than the thickness of thelaminatlon. As more clearly shown by the tcp view of the Fig. 2b, each of the laminations I9 has an aperture 38 centrally positioned with relation to the indentation 31 and concentric with the axis o-o of the connector. The contact fingers 35 are formed by serrating the laminations I9 radially with respect to the axis lo---o to a radial depth approximately equal to the outer diameter of the indentation 31. A relatively rigid ring 39, shown more clearly in Figs. 2a and 2b, preferably is used tov maintain the laminations I9 firmly clamped in assembled relation. k

Fig. 3 illustrates a suitable method by which the laminations I9 are formed. Starting with a flat disc of conductive material, the concentric groove 31 is rst stamped into one face of the maf teria] while at the same time the central portion, indicated by the broken-line portion 40, of

the disc is pressed upwardly above the'face of the 75 s. disc. The central portion Il of the disc is punched out to provide thecentrai aperture 3l' and the disc is then slotted radially by asawing or punching operation to provide thev contact nsers 3B. It will be apparent that while these steps have been described. as successive steps in\ theformation oi'f the lamination, one or more such steps may be combined into a single step. For

example, the serrations may beformed by the same die which punches out the central portion lil of the lamination.

It is preferabley as a finishing step of the connectorV construction that the laminations i9 be stacked in assembled relation and the central aperture 33 be then ground `or lapped toadiameter slightly smaller than that of the contact member with which the connector is used. This ensures the maximum area of contact surface of the ends of the fingers 33 with the contact member and at the Sametime removes any burrs which may be formed at the inner ends of the contact fingers during oneor more of the forming steps previously described. Alternatively, the contact surface S of the connector may be brushed with a steel-wire brush` rotating about the axis o-o of the laminations. This brushing operation serves primarily to remove any burrs at the inner ends of the contact fingers.

Where the connector of the present invention is lused. to engage the anode terminal of a vacuum tube as in the particular application hereinbeforedescribed, it is preferable that the aperture 3B of the connectorjhave a diameter a few thousandths of an inch smaller than the diameter of the anode terminal in order that the laminations at the inner ends of the contact fingers 35 may flex over a limited range of movement as indivi ual laminations substantially out of contact w th one another. This reduces to a kveryminimum the force required to make vand to break contact of the anode terminal withy the connector while yet ensuring adequate and consistent thermal and electrical contact therebetween. In an actual embodiment of this type, the diii'erence in diameters of the` aperture 33 and the anode terminal member was made of the order of 0.005 to 0.010 inch. i

1f the endyof each contact finger of an individual lamination lies substantially in theplane lamination since this introduces a very slight locking effect against withdrawal of the contact member from fully engaged relation with the connector.- In the actual embodiment last mentioned, the contact fingers were so formed thatthe ends thereof extended 0.30 inch above the planeof the serration roots.

It will ,be apparent from the above description of the invention that an electrical connector embodying the invention provides positive, consistent and substantially uniform-electrical' and'thermal contact with a cylindrical contact member when the latter is in engaging relation therewith. There is the further advantage that the force required to effect complete engagement of the contact member with the connector is minimized while, at the same time, relative lateral and angular departures from coincidence of the axes of the connector and contact member are permitted. There is the additional advantage that the electrical connector is of relatively simple and inexpensive construction and is well adapted to mass production techniques.

While there has been described what is at present considered to be the preferred embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

l. An electrical connector adapted to engage an approximately cylindrical conductive contact member comprising, stacked laminations of resilient conductive material having nested V- shaped contact fingers arched normal to the plane of' lamination and extending radially with respect to a common axis to provide at their inner ends a cylindrical laminated contact surface normally symmetrical about said common axis but deformable to maintain coincidence of the axis of said contact surface with that of said contact member when said member is positioned in engaging relation with said surface, whereby said connector is adapted to ensure consistent and substantially uniform electrical and thermal contact with said contact member while minimizing the force required to effect complete engagement of said member with said connector.

2. An electrical connector adapted to engage an approximately cylindrical conductive contact member comprising, stacked laminations of resilient conductive material having nested V- shaped contact fingers arched normal to the plane of lamination and extending radially with respect to a. common ax'm to provide at their inner ends a cylindrical laminated contact surface normally symmetrical about said common axis but deformable to maintain coincidence of the axis of said contact surface with that of said contact member when said member is positioned in engaging relation with said surface, and means for spacing said laminations at the outer ends of said contact fingers tc permit increased conjoint flexibility of said laminations at the inner ends of said fingers, whereby said connector is adapted to ensure consistent and substantially uniform electrical and thermal contact with said contact member while minimizing the force required to effect complete engagement of' said member with said connector.

3. An electrical connector adapted to engage an approximately cylindrical conductive contact member comprising, stacked laminations of resilient conductive material having nested V- shaped contact fingers arched normal to the plane of lamination and extending radially with respect to a common axis to provide at their inner ends a cylindrical laminated contact surface normally symmetrical about said common axis but deformable to maintain coincidence of the axis of said contact surface with that of said contact member when said member is positioned in engaging relation with said surface, and spacing laminations inserted between said first-mentioned laminations at the outer ends of said contact fingers to permit increased conjoint flexibility of the inner ends of said fingers, whereby 8 said connector is adapted to ensure consistent and substantially uniform electrical and thermal contact with said contact member while minimizing the force required to effect complete en- :agement oi said member with said connector.

4. An electrical connector adapted to engage an approximately cylindrical conductive contact member comprising, stacked laminations of resilient conductive material having nested V- shaped contact fingers arched normal to the plane of lamination and extending radially with respect to a common axis to provide at their inner ends a cylindrical laminated contact surface normally symmetrical about said common axis but deformable to maintain coincidence of the axis of said contact surface with that of said contact member when said member is positioned in engaging relation with said surface, a mounting member having a surface for supporting said laminations at the outer ends of said contact fingers, and means for securing said laminations to said mounting member to provide a unitary connector structure, whereby said connector is adapted to ensure consistent and substantially uniform electrical and thermal contact with said contact member while minimizing the force required to effect complete engagement oi said member with said connector.

5. An electrical connector adapted to engage an approximately cylindrical conductive contact member comprising, a plurality of laminations each of resilient conductive sheet material having integrally formed contact fingers arched to have s V-shaped configuration normal to the plane of lamination and extending radially with respect to a common axis, said laminations being stacked with said contact fingers in nested relation to provide at the inner ends of said fingers a cylindrical laminated contact surface normally symmetrical about said common axis but deformable to maintain coincidence of the axis of said contact surface with that of said contact member when said member is positioned in engaging relation with said surface, whereby said connector is adapted to ensure consistent and substantially uniform electrical and thermal contact with said contact member while minimizing the force required to effect completc engagement of said member with said conntcr.

6. An electrical connector adapted to engage an approximately cylindrical conductive contact member comprising, a plurality of laminations of resilient conductive sheet material each having a central aperture with radial serrations extending therefrom to provide a plurality of integrally formed contact fingers arched to have a V-shaped configuration normal to the plane of lamination and-extending radially with respect to a common axis, said laminations being stacked with said contact fingers in nested relation to provide at the inner ends of said fingers a cylindrical laminated contact surface normally symmetrical about said common axis but deformable to maintain coincidence of the axis of said contact surface with that of said contact member when said member is positioned in engaging relation with said surface, whereby said connector is adapted to ensure consistent and substantially uniform electrical and thermal contact with said 70. contact member while minimizing the force required to effect complete engagement of said member with said connector.

7. An electrical connector adapted to engage an approximately cylindrical conductive contact member comprising, a plurality of laminations y 9 each oi' resilient conductive sheetmaterial having a ring indentation of V-shaped ring section formed in one falce thereof to a depth much greater than the thickness of said lamination and having an aperture centrally of said indentation with radial serrations extending therefrom to provide a plurality of integrally formed V-shaped contact lfingers arched in a direction normal to the plane of laminations and extending radially "with respect to a common axis, said laminations being stacked with said contact' lingers in nested relation to provide at the inner ends of saidl fingers a cylindrical laminated contact surface normally symmetrical about said common axis but deformable to maintain coincidence of the axis -oi said contact surface with that of said contact member when said member is positioned in engaging relation with said surface. whereby said connector is adapted to ensure consistent and substantially uniform electrical and thermal contact with said contact member while minimizing the force requiredvto effect complete ensagement of said member with said connector. l

- BASlL A. BELS.

REFERENCES CITED The following references are of record in the ille of this patent:

FOREIGN PATENTS Number Country Date 552,995 lGermany June 20, 1932 519,478 Great Britain Mar. 28, 1940 369,342 Great Britain Mar. 24, 1932 

